Specifically, FairUse4WM works only on Windows Media DRM 10 and DRM 11 (aka, PlaysForSure). While "this program is ONLY designed and intended to enable fair-use rights to PURCHASED media," as it stands, the program will strip the DRM from any PlaysForSure file, whether you've purchased or just rented the song. So it's really up to you to ensure the fair use of this program and your music.

As someone who's not too keen on the current state of DRM, I can say that FairUse4WM is definitely a tool I'd recommend using under the right circumstances. Let us hear your thoughts on this snazzy new music liberator in the comments or at tips at lifehacker.com. — Adam Pash